COMPARISON OF SEROLOGICAL TESTS FOR THE DETECTION OF ANTIBODIES AGAINST CHLAMYDIA-TRACHOMATIS AND CHLAMYDIA-PNEUMONIAE IN RHEUMATOLOGICAL PATIENTS

In cases of reactive arthritis, a suspected Chlamydia trachomatis infe ction is often detected by serological methods. However, mostly tests with genus-specific antigens are used, neglecting the fact that antibo dies against Chlamydia pneumoniae are highly prevalent in the adult po pulation. Therefore we tested sera of 129 patients with various rheuma tological disorders and of 18 healthy persons in parallel with a genus -specific test (IPAZYME(R)) and with the species-specific microimmunof luorescence test for C. trachomatis and C. pneumoniae antibodies. The data showed that 55% of the 64 IPA-positive results were caused by ant ibodies (IgG) against Chlamydia pneumoniae, only 6% by anti-Chlamydia trachomatis IgG and 20% by both specificities. For IgA antibodies, the percentages were 44%, 12.5% and 12.5% respectively. In 12 IPA-positiv e cases, the MIF showed no reaction. 58% of all 147 sera tested with M IF had IgG antibodies against C. pneumoniae, 5% had anti-C. trachomati s IgG and 8% IgG against both species. The percentages for IgA were 29 %, 2% and 2%, respectively. IgM positivity in MIF disappeared after ab sorption with rheumatoid factor absorbent. No significant differences were found between the various groups of patients. The data suggest th at due to the high prevalence of anti-C. pneumoniae antibody, genus-sp ecies tests cannot be used as screening tests for the serological diag nosis of C. trachomatis infections.